"Brian came up to my house a couple of weeks ago, and we started talking about it again – but it’s quite possible," Iommi told EON Music. "We’d like to do it, but now he’s going on tour. But yeah, I’d like to do something with him."

We got a preview of how the pair would work together when May appeared on the Black Sabbath guitarist's self-titled 2000 solo album, guesting on the track "Flame On." That led to a larger conversation about making music together in 2013. Back then, they were hoping for an interactive project where fans would complete the songs. "The idea was to put all these riffs out in some form," May said, "so that people could build their own songs from them."

Iommi ended up focusing on Black Sabbath as they headed toward their final shows with Ozzy Osbourne. Meanwhile, May and fellow Queen co-founding member Roger Taylor have been touring with singer Adam Lambert.